Tennis Australia is refining the heat rule for the Australian Open.

The heat is on. Australia has been sweltering in very hot summer conditions while the northern hemisphere bears up with the winter chills. The Australian Open remains one of the hottest tournaments in the world with temperatures and with that Tennis Australia announced its full guidelines for heat rules.

The more extensive Extreme Heat Policy (EHP) to be introduced at in a couple of weeks time at the year’s first major as a result of cutting-edge research and testing into the specific effects of heat stress on tennis players.

The research, conducted by Tennis Australia medical personnel in conjunction with the Thermal Ergonomics Laboratory at the University of Sydney, has led to the development of the AO Heat Stress Scale (AO HSS).

Key features include:
* The newly developed AO Heat Stress Scale
* More comprehensive measuring of weather conditions at Melbourne Park
* An increase in measuring devices across the site
* A 10-minute break for men’s singles (to go with the 10-minute break already in place for women’s singles and junior singles, and the 15-minute break for wheelchair singles) 

Australian Open Tournament Director Craig Tiley said his team was constantly looking for ways to improve the conditions for the players.

“The wellbeing of all players at the Australian Open is our utmost priority and we have developed the Australian Open Heat Stress Scale after months of research and testing,” Tiley said.

“The AO Heat Stress Scale ranges from one to five with specific recommendations associated with each step of the scale – one denoting temperate playing conditions and five the suspension of play.

“Under the updated policy, 10-minute breaks can also be introduced into men’s singles matches for the first time.”

Tennis Australia’s Chief Medical Officer Dr Carolyn Broderick added: “The AO Heat Stress Scale takes advantage of the latest medical research into the effects of heat on the human body including the maximum heat stress an athlete can safely withstand, the sweat rate of that person and their core temperature,” 

“The scale also accounts for the physiological variances between adults, wheelchair and junior athletes while also taking into account the four climate factors – air temperature, radiant heat or the strength of the sun, humidity and wind speed – which affect a player’s ability to disperse heat from their bod.”

With new technology and information available, these four climate factors will be accurately measured in real time at five different locations across the Melbourne Park precinct. This provides more information than the previous Wet Bulb Globe Temperature (WGBT) readings from the Bureau of Meteorology.

Looks like we are done with that comically named and complicated Wet Bulb concept. 

Under the EHP, the Tournament Referee will allow a 10-minute break between the second and third sets in both women’s and junior singles matches and a 15-minute break in wheelchair singles matches when a four (4.0) is recorded on the AO HSS prior to or during the first two sets of the match.

In the men’s singles a 10-minute break will be allowed after the third set when a four (4.0) is recorded on the AO HSS prior to or during the first-three sets of the match. 

If a five (5.0) is recorded on the AO HSS, the Tournament Referee can suspend the start of matches on outside courts and all matches in progress continuing until the end of an even number games in that set or completion of the tie break before play will be suspended.

Matches on Rod Laver Arena, Margaret Court Arena and Melbourne Arena will stop after an even number of games in that set or completion of the tie break when the Tournament Referee can decide to close the roof for the remainder of the match and the following matches, when the EHP is still in effect.

PS: the roof over Rod Laver Arena has been upgraded as well and will now take just five minutes to open and close.